That is the question haunting the University of California, Berkeley, which is engaged in a $321 million upgrade of its football stadium in the midst of the worst budget crisis in its history.

As the Cal Bears get ready to open their home season on Saturday at AT&T Park, their temporary residence, university officials are eyeing the progress of an elaborate financing plan for California Memorial Stadium that relies on selling 50-year rights to 3,000 special seats for $40,000 to $225,000 each.

If the seats get sold, Cal will be able to pay off the stadium renovation and establish an endowment to support all of its athletic programs. But if sales fall short, the university could be on the hook for tens of millions in construction costs even as it wrestles with up to $80 million in budget cuts for the next fiscal year as well as plans for huge tuition increases.

So far, the results are mixed. After an initial surge in interest, seat sales have slowed over the past year, and Cal is only halfway to its goal. In its latest update, at the end of June, the athletic department reported 49 percent of the 3,000 Endowment Seating Program seats were sold. But the total projected revenue of $113.5 million is just 41 percent of the goal, and only $27.8 million has been collected; buyers can pay up front or over time, but there is no contract, so people can opt out at any time.

The seats that have sold the best are those at the lowest price; there have been few takers at $225,000.

“It’s ambitious, and it’s optimistic,” said Roger Noll, a Stanford economist and a leading academic authority on stadium financing. “And, unfortunately, they’re going to have to commit to spending $350 million before they know whether they’ll get the revenue.”

The stadium upgrade, and the recently completed $150 million Student Athlete High Performance Center, are the handiwork of Cal’s intercollegiate athletics department, which has struggled financially for years. According to a report by the university’s academic senate, the department required almost $9 million annually from the general campus fund from 1999 to 2009. The figure for last year was $10.5 million, and Cal has vowed to reduce it to $5 million by 2014.

The stadium financing plan was created in 2008, when the football team was on a roll under Coach Jeff Tedford. The UC Regents had ordered the campus either to fix the stadium — it sits on top of the Hayward fault in a ravine above the Berkeley campus — or to find a new place for the Bears to play.

Cal contracted with Stadium Capital Financing Group of Chicago, an affiliate of Morgan Stanley, and developed the ESP seat-selling plan. The goal was to raise $250 million, with much of the money coming up front. Some of the money would go into an endowment, which would provide lasting support for all Cal athletic programs (budget cuts last year nearly killed off five sports, including the baseball program).

“The fans and donors we’re talking about have a bigger picture in mind: to create this endowment,” said Sandy Barbour, the Cal athletic director.

The seats are a key part of the stadium renovation, which also includes wider concourses and seats, more concessions and restrooms, and improved wheelchair access. The extra-plush ESP seats are outdoors, and there are three levels, each with its own amenities and price tag. (Cal alumni had made it clear in surveys that they did not want to be separated from the rest of the fans in enclosed luxury boxes.) ESP participants also receive parking passes, and access to the stadium and clubs on nongame days.

Barbour said that ESP had “altered” its financial aspirations, but that most sales are likely to come this year and that she still has faith that all the seats will be sold.